How to get a Fresnel node to only affect one part of an object? Ie) The top of an object
You are currently blending the fresnel and topside(normal) masks using a mixRGB node set to "mix". This gives you a blend of both masks. Sounds like what you're actually after is the area where both masks are non-zero, so the blending option you want is "multiply". You can either change the mode on the mixRGB node to "multiply", or replace it with a math node since these are float values (grey socket) rather than vectors/colors.